1. Field of the Invention
The present invention relates to a technology for realizing both silence and performance at a low cost in a storage apparatus having a disk-like recording medium and a movable head.
2. Description of the Related Art
A storage apparatus that performs a data input/output with respect to a disk-like (circular) recording medium, such as a hard disk drive, is currently in use. In such a storage apparatus, a movable head is shifted to a predetermined position on a disk by a driving device such as a voice coil motor (VCM), for the data input/output. Because needs for a speedup of data access is increasing, there is a tendency that a shifting speed of the head is also increasing.
In addition to the needs for the speedup of data access, there are also needs for assuring silence of the storage apparatus. Particularly, in recent years, because of market needs that emphasizes silence of a personal computer and the like, the silence of the storage apparatus (for example, the hard disk drive) to be loaded is also demanded.
However, in a conventional hard disk drive, when an improvement in the shifting speed of a head is intended, the noise (seek noise) level is raised by a rapid change in VCM current resulting from an acceleration/deceleration of the head. In other words, there is a trade-off between a reduction of the seek noise and the speedup of data access.
For example, Japanese Published Unexamined Patent Application No. H10-326470 discloses a technique for preparing-several-types of voltage waveforms to be applied to the VCM and allowing a user to select a mode where data access time is long despite a small seek noise or a mode where data access time is short despite a large seek noise.
However, because the above technique is for selecting either a reduction in seek noise or a reduction in data access time, both a reduction in seek noise (silence) and reduction in data access time (performance) cannot be realized.
Both the reduction in seek noise and the reduction in data access time can be realized by soundproofing of noise (seek noise) generated due to a speedup of head shifting speed. However, if a disk drive is covered with a cover containing a sound absorbing material or the cover itself is thickened, a problem of increasing manufacturing cost or an increase in the size of the drive itself arises.
Based on these circumstances, there has been a major challenge in how to realize the hard disk drive having both silence and performance at a low cost. Such a challenge is common, not limited to hard disk drives, for other storage apparatuses (for example, optical disk drives) in general that use movable heads for data access.